Component age estimates for the Hell Gap Paleoindian site and methods for chronological modeling of stratified open sites

The Hell Gap National Historic Landmark, located on the northwestern plains of Wyoming, is one of the most important Paleoindian archaeological sites in North America because it contains a stratified sequence of occupations spanning nearly the entirety of the Paleoindian period. Although Hell Gap is central to archaeological knowledge concerning North American Paleoindian chronology, consistently assigning component ages has been problematic due to conflicting radiocarbon determinations from individual strata, stratigraphic age reversals in age-depth relationships, and other issues related to the stratified open campsite. Toward resolving the Hell Gap chronology, we devised a procedure for correcting age-depth relationships for incorporation in chronostratigraphic models and then used the Bayesian age-depth modeling qprocedures in Bchron to estimate the ages of 11 stratified components present at Hell Gap Locality 1. We present these age estimates and discuss their significance to Paleoindian chronology. Notable aspects of our chronology include a revised age estimate for the Goshen complex, the identification of three Folsom components spanning the entirety of the Folsom temporal range, and relatively young age estimates for the Late Paleoindian Frederick/Lusk component(s) at Locality 1. More broadly, our study demonstrates a procedure for creating chronometric models of stratigraphically complicated open stratified sites of any type.

Redating the Mill Iron Site, Montana: A Reexamination of Goshen Complex Chronology

The Paleoindian Goshen complex occurs in the northern Plains and eastern Rocky Mountains. Since its identification, there has been much discussion about the chronological placement of the Goshen complex. This is especially true because diagnostic Goshen projectile points occur stratigraphically below Folsom artifacts at two sites, and early dates from the Mill Iron site, Montana, and the Hell Gap site, Wyoming, have suggested that this point type might be coeval with Clovis or the very earliest Folsom sites. This report presents new radiocarbon dates from the Mill Iron site, reviews Goshen chronology, and revises the age of the Goshen complex as 10,450 ± 15 to 10,175 ± 40 radiocarbon years B.P.